1. Field of the Invention
The invention relates to a system and to the apparatus thereof for the continuous removal and destruction of halogenated aromatic hydrocarbons from fluids. More particularly, the invention relates to a system and to the particular apparatus and arrangement thereof for the continuous removal and destruction of toxic polychlorinated biphenyls from oils which are used as the cooling fluids for transformers and for dielectric materials of electric capacitors.
2. Description of the Prior Art
Polychlorinated biphenyls (PCBs) are very stable compounds which are not destroyed by natural processes. Recently, their use has been banned for environmental reasons due to the possible danger to the environment and inhabitants. PCBs are not destroyed by natural processes and they are not biodegradable and will not disappear or decay to any extent by natural processes. Once they are formed, they can be destroyed only by special and expensive procedures.
Because of their terminal stability and nonflammable properties, PCBs have been used extensively as electrical insulating fluids and in dielectric materials such as in transformers and in capacitors. Although further use of PCBs for such purposes has been banned, huge quantities of these chemicals are present in the country today, especially in the electrical industry. Also, there is a vast amount of PCBs in storage awaiting a sure and inexpensive method of disposal. PCBs can be burned but only at a very high temperature and under rigidly controlled conditions. To date, incineration programs have not been entirely successful. PCBs also have been disposed of by burial, but this means of disposal presents the same risks that discourage the burial of any hazardous substance. Presently, the only known methods and means of disposal of PCBs are very costly and inefficient.
By the time PCBs were recognized as a hazard to health and the environment, they were widely disseminated in all compartments of the biosphere. Except in those instances where the concentration is great and the contaminated area is small, little can be done to correct the problem. Only time can do so, and the extraordinary stability of these chemicals suggests that it will be an exceedingly long time for destruction of these chemicals by natural processes. Due to the vast quantities of PCBs still in use today, eventual escape of these materials into the environment can be prevented only by an effective program and system for their destruction. It is estimated that oil-insulated transformers alone which are contaminated with more than 50 ppm of PCBs account for six hundred million gallons of contaminated oil. Add to this all the pure PCBs still in use for other purposes, and it is apparent that sooner or later a major portion of these PCBs will find their way into the environment unless a satisfactory means of disposal or destruction of PCBs is developed.
The incineration of the PCB-contaminated transformer oil used by some segments of the industry today results in the destruction of approximately twelve thousand pounds of transformer oil to get rid of approximately one pound of PCB. Likewise, the burial or incineration of PCBs or materials contaminated therewith also requires risky transportation to approved disposal sites, with the resulting dangers always present therewith.
A method for chemically removing PCBs and similar halogenated aromatic hydrocarbons from oils contaminated with such hazardous materials is disclosed and claimed in abandoned application, Ser. No. 99,341, filed Nov. 30, 1979. The present invention described below is a unique system and arrangement of equipment for carrying out this chemical method on a continuous large-scale effective commercial basis.
Presently there are two known processes for the continuous separation of PCBs from fluids which are contaminated with such materials, such as transformer oils. However, the apparatus and particular equipment for these systems are believed to be more complicated and expensive than that of the present invention and would be difficult to install in a self-contained mobile unit which can be transported to the site of the contaminated oil. Both of these known processes and the limited description of the system and equipment thereof are contained in the prior art publications listed in the Prior Art Statement of the present invention.